Firing mechanism for automatic guns



June 23, 1953 H. TREVASKIS FIRING MECHANISM FOR AUTOMATIC suns 3 Sheets-Sheet 1 Filed Oct. 4, 1945 .||IV ll,

INVENTOR. /7E/VEY 7'95 VASk/S mwww June 23, 1953 H. TREVASKIS 2,642,779

FIRING MECHANISM FOR AUTOMATIC GUNS Filed Oct. 4, 1945 3 Sheets-Sheet 2 O O O IN VEN TOR. flay/er 7% 1445/05 ,4 Tram 5y June 23, 1953 H. TREVASKIS FIRING MECHANISM FOR AUTOMATIC GUNS 5 Sheets-Sheet 3 Filed Oct. 4, 1945 JNVENTOR. flwey Kama/(w BY Arme/uey I /ia. f7

Patented June 23, 1953 UNITED STATES ATENT OFFICE FIRING MECHANISM FOR AUTOMATIC GUNS Application October 4, 1945, Serial No. 620,200 In Great Britain October 14, 1944 My invention has reference to improvements in or relating to firing mechanism for automatic guns more especially guns of the Hispano type and is concerned particularly with firing mechanism for such guns of the kind in which the tripping of the sear is effected through .the agency of an electromagnetically actuated trigger device.

The present invention has for its primary object to provide an improved firing mechanism of the aforesaid kind which is of a relatively small depth thus rendering the improved firing mechanism particularly suited for guns which are required to be fitted within the wings of aircraft by permitting of the reduction of the dimensions of or the elimination of the external fairing which is generally required for enclosing such parts of the firing mechanism as it is not possible to contain within an aircraft wing.

Further objects of the invention are to provide a firing mechanism of the aforesaid kind which is economical in current consumption and which can readily be attached to or removed from a gun as a unit assembly.

According to the invention an improved firing mechanism for automatic guns of the kind hereinbefore referred to comprises a mounting plate adapted to be secured to a fixed part of a gun adjacent to the sear, a firing assembly comprising a solenoid device and a trigger member, said solenoid device having a winding contained between end plates and a circumferential shell and a centrally movable core and said trigger member being disposed perpendicular to the axis of said core, which member is pivoted at one end on one of said end plates, bears on the sear at the other end and is connected to the core intermediate its end, and means to attach the firing assembly to the mounting plate.

Moreover, according to the invention the improved firing mechanism preferably incorporates an electrical resistance which is brought into circuit automatically to reduce the consumption of electric current required to hold the trigger device in the sear tripping position after a tripping has been effected.

The invention still further resides in the details of construction of the improved firing mechanism to be described hereinafter.

The invention will now be described with particular reference to the accompanying drawings which illustrate the improved firing mechanism as adapted for use with a 20 mm. Hispano automatic gun.

The various features of my invention are illustrated, by way of example, in theaccom- Claims. (Cl. 89135) panying drawings in which, Fig. l is a longitudinal vertical section of a firing means embodying a preferred form of the invention in po sition relative to a part in a gun of the Hispano type shown in broken lines;

Fig. 2 is a plan of the firing mechanism illustrated in Fig. 1;

Fig. 3 is a vertical section on line 3-3 of Fig. 2 on a larger scale of certain elements of the firing mechanism;

Fig. 4 is a vertical section of the firing mechanism taken on line 4-4 of Fig. 1;

Fig. 5 is a vertical section taken on line 5--5 of Fig. 2;

Fig. 6 is a wiring diagram of the electric circuits of the firing mechanism;

Fig. 7 is a perspective view of elements for retaining the firing mechanism on the gun, certain parts being shown lifted free and turned upwardly to illustrate the construction, and being shown partly in section;

Fig. 8 is a vertical section on a larger scale of the lower part of a magnetic core and closing blade and switch elements forming a part of the firing mechanism.

In the drawings like numerals of reference indicate similar parts in the several views.

As illustrated the improved firing mechanism incorporates a mounting plate I which is adapted to be screwed to the underside of the part of the gun housing the sear 8, Fig. 1. This mounting plate 1 is adapted to have attached thereto in a manner to be described an assembly which i built round the end plates 9a, 9b of a solenoid device, the winding of the solenoid device being indicated by the reference numeral [0.

The upper end plate 9a. is provided with an aperture within which is disposed a vertically movable core II. The upper portion of this core i l is provided with a pair of longitudinal grooves I la which serve to accommodate the twin beams 12 of a trigger member, Figs. 1 and 2, which will be referred to henceforth compositely as the trigger member I2. The trigger member I2 is fulcrumed at one end to a post 13a secured to the upper end plate 9a whilst the other ends which are rounded bear on complementary surfaces 80, forming part of the toe of the sear 8, Fig. 1. Intermediate its ends and at a position which is more remote from the fulcrum than from the sear engaging end the said trigger member I2 is pivotally connected to the core H by means of a transverse pin l3 the axis of which is located in the same plane as the vertical axis of the core I l.

I he lower end of the core H is serrated as at placement by means of a circlip I5, said cap I4 serving as an abutment for the lower end of a volute spring I6 the upper end of which abuts a metal plate IT The spring I6 maintains the metal plate I 'I in contact with two electrical contacts I8a, I8b one of which namely I8a is in electrical connection with an end of the solenoid winding IO and with an end of a resistance winding I9, Fig. 6, Whilst the other contact namely I8b is in electrical connection with'the other end of the resistance winding I9 and with one of the poles of the current supply. Normally and as shown in Figs. 4, 6 and 8 the metal plate I'l bridges the contacts I8a, IBb so that the circuit is completed through the mainwinding I'll only.

The metal plate I! is formed with an upstanding central portion I'Ia; which is axially arranged relatively to a pin which projects downwardly from the centre of the core I I.

The pin 20 and the adjacent end' of the upstanding central portion I'Id are normally spaced apart under the influence of a coil spring 2I which is arranged concentrically about the said pin 20 and which is located at one end within a recess in the core I I and at the other end within a recess in the lower end plate 9b, Fig. 8.

Connection with a source of electric power is made by a plug and socket coupling, the socket element of which is of the two pin type and is mounted on the rear end of the lower plate 9?) denoted by the reference 22. This socket 22 is provided with a spring controlled catch 23, Figs. 1 and 5, which when the plug element (not shown) is in engagement with the said socket 22 engages within a recess in the plug element and locks the said plug element within the socket 22. When it is desired to remove the plug element the catch 23 is disengaged from the said recess by moving the catch by means of the serrated finger grip 23a. 7

The forward end of the upper end plate 9a. is formed with a tapped cylindrical hole 9d which serves to accommodate a screw threaded sleeve 24, said sleeve having a head 240. which has a serrated periphery and which is of a greater diameter than the hole 9d.

The bottom of the bore in the sleeve 24 'is closed by a disc 25 which serves as an abutment for the lower end of a coil spring 26 the upper end of which abuts the underside of a collar 21a formed intermediate the ends of a plunger 21, the lower portion of which depends within the upper portion of the said spring 26. Theupper end of the plunger 21 tends to project above the plane of the mounting plate I under the influence of the spring 26 so that when the assembly is in position on a gun as illustrated in Figure 1 the plunger bears on the sear 8 adjacent to the heel thereof and so tends to maintain the sear in engagement with the breech bolt of the gun. a

Adapted to bear on the head 24a of the screw threaded sleeve 24 are the noses at a pair of 4 thimbles 28 Figs. 1 and 3 the lower ends of which serve as abutments for coil springs 29 Fig. 4 which are arranged concentrically within the said thimbles 28. The upper ends of the springs 29 abut the undersides of the arms of a wedging member 30 the wedge face 30a whereof co-coperates with a complementary wedge face Ia carried by the mounting plate 7.

. When the sleeve 24 is screwed into the mounting plate the head 24a of the sleeve compresses the springs 29, and the wedging member 30 is thereby urged upwards and forces the bevelled edges 32 of the mounting plate and the comple- V mentary undercut faces 33 of the upper end plate into engagement, thus holding the firing assem- V "bly rigidly against the mounting plate.

When it is desired to detach the assembly from the gun the sleeve 24 is first unscrewed and the assembly is then loosely held by engagement of the faces 32 and 33. Complete disengagement of these faces is prevented by the shoulder on the upper end plate which abuts against the bufier block 3| at 35. This block can be raised about 0.4 by pulling .out of engagement a lock 34 forming part of the construction of the gun,

and when this is done sufficient clearance is given between the shoulder and the block for the undercut faces 33 to slide out of engagement with faces 32. f

Attachment of the assemblyis effected by raising the block 3|, sliding the faces 33'into engagement with the faces 32 and allowing the block to return to position. The assembly is then loosely held between the faces 32' and the block and can be rigidly attached to the mounting plate by screwing up the sleeve 24 as described above.

The firing mechanism operates in the following manner:

When it is desired to fire a gun the usual contol (not shown) is manipulated to close the circuit through the winding Ill. This results in the energisation of the solenoid device and as a consequence causes the core II to be drawn downwardly. Downward movement of the core II turns the trigger member I2 about its fulcrum and causes the nose of the said member I2 to bear on the sear Band to trip the said sear out of engagement with the breech bolt thus permitting the weapon to fire. v

During the downward movement of the core I I the pin 20 comes into contact with the upstanding portion I10. and presses the said portion Ila and the associated plate ll downwardly thus allowing the spring contacts I, and Nb to break contact so that the resistance winding I9 is brought into circuit toreduce the amount of the current flowing through the winding II). The reduction in. current consumption in the embodiment described is of the order of from 10 amperes to 3 amperes, but it will be understood that a current of the latterorder is. sufiicient to maintain the core II' in the retracted position once the initial retraction has been eiiected thus permitting of automatic operation of the weapon at a reduced-current consumption whilst the firing circuit is completed.

When the firing control is released the core II and hence the trigger member I2 are moved to the positions shown in Figure 1 and the sear 8 moves to engage the breech bolt under the infiuence of the spring pressed-plunger 2-1.

It will be appreciated that by arranging for the trigger member I2 to be mounted horizon-- tall-y with the sear engaging endmore remote from its pivotthanitspoint of connection to the moving core H of the solenoid device a full displacement of the sear engaging extremity is obtained for a reduced displacement of the moving core I I relatively to that which is necessitated in prior practice, so that a solenoid of lesser depth is required.

Thus the invention provides a firing assembly which is of small depth thus rendering it of particular advantage for guns which are required to be mounted in the wings of aircraft since either no fairing at all will be required as no part of the firing mechanism will be exposed or else a smaller fairing will be required than has been necessary heretofore as a smaller part only will be required to be enclosed by such a fairing.

In addition it will be appreciated that the firing mechanism can be atached to a gun and detached as a unit assembly with great facility.

7 Having described my invention-what I claim is:

1. A firing mechanism for automatic guns which comprises a mounting plate to be secured to a fixed part of a gun adjacent to the sear thereof, a firing asembly comprising an upper and lower plate and a shell between said plates to form a solenoid casing, a solenoid winding within said casing, a movable core extending from above said mounting plate through said upper casing plate and axially within said winding, a trigger member disposed perpendicularly to the axis of said core and pivoted at one end to said upper plate and extending to engage a sear at its other end and secured to said core intermediate said ends, said mounting plate and upper plate having complementary undercut surfaces to hold them into engagement, said mounting plate having a second surface inclined from the vertical in a direction opposite to the incline of said undercut surface, a movable wedging member having a surface complementary to said second inclined surface and a spring pressing said wedge shaped member into engagement with said inclined surface.

2. A firing mechanism for automatic guns which comprises a mounting plate to be secured to a fixed part of a gun adjacent to the sear thereof, a. firing assembly comprising an upper and lower plate and a shell between said plates to form a solenoid casing, a solenoid winding within said casing, a movable core extending from above said mounting plate through said upper casing plate and axially within said winding, a trig er member disposed perpendicularly to the axis of said core and pivoted at one end to said upper plate and extending to engage a scar at its other end and secured to said core intermediate said ends, said mounting plate and upper plate having complementary undercut surfaces to hold them into engagement, said mounting plate having a face inclined in a direction opposite to that of said undercut surfaces, a tapped orifice in said mounting plate, a screw threaded in said orifice, a plunger slidably mounted on said firing "assembly having an inclined face complementary 6 to that on said mounting plate and a spring confined between said screw and said plunger to press said plunger against said inclined face.

3. A firing mechanism for automatic guns which comprises a mounting plate to be secured to a fixed part of a gun adjacent to the sear thereof, a firing assembly comprising an upper and lower plate and a shell between said plates to form a solenoid casing, a solenoid winding within said casing, a movable core extending from above said mounting plate through said upper casing plate and axially within said winding, a trigger member disposed perpendicularly to the axis of said core and pivoted at one end to said upper plate and extending to engage a sear at its other end and secured to said core intermediate said ends, said mounting plate and upper plate having complementary undercut surfaces to hold them into engagement, said mounting plate having a face inclined in a direction opposite to the incline of the undercut surface of said mounting plate, a tapped orifice in said mounting plate, a screw threaded therein and a plunger on said firing assembly and actuated by said screw against said inclined surface of said mounting plate.

4. A firing mechanism for automatic guns which comprises a mounting plate to be secured to a fixed part of a gun adjacent to the sear thereof and having an undercut face, a firing assembly comprising a solenoid device and trigger member, said firing assembly having a complementary undercut face to engage the undercut face of said mounting plate, said mounting plate havin a wedging face inclined in a direction opposite to that of its undercut face, a movable wedge on said firing assembly having an inclined surface complementary to the wedging face of said mounting plate and spring pressed means to move said movable wedge shaped member into engagement with said inclined face.

5. The firing mechanism of claim 4 comprising a tapped orifice in said mounting plate, a screw threaded therein, a plunger mounted on said screw and spring means for pressin said plunger into engagement with said sear to move said sear into bolt retaining position, said screw also being positioned to engage said spring means acting on said wedge shaped member.

HENRY TREVASKIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 922,268 Dawson et al May 18, 1909 946,215 Geissinger Jan. 11, 1910 2,331,942 Turnbull Oct. 19, 1943 2,337,145 Albree Dec. 21, 1943 2,344,178 Sparrow Mar. 14, 1944 2,380,262 Quinnell et a1 July 10, 1945 FOREIGN PATENTS Number Country Date 312,236 Germany May 21, 1919 

